High tensile alloy steel



Patented-Ian; 9,1940

.1: n w; semi HIGH TENSILE ALLOY s'rEEL' WilliamHerbertnHatfield, sherrlels, England, as-

signorto Thus. Firth &' John Brown Limited; Sheffieid, Yorkshire, England, a British com- No Drawing. Application December 410,,1937,

Serial No. 179,123. In Great Britain February high tensile alloy steeL.

In order to obtain steels of high tensile strength for structural purposes and other high duty applications it has been general practice to employ the addition of certain elements to the composition, which in conjunction Withthe carbon content rendered the steel capable of being hardened and tempered, the latter operation giving a degree of control over the residual hardness and tensile strength in conjunction with the eliminae tion of brittleness generally left as a result of the hardening operation.

The "present invention relates to a new com binationof iron and alloying elements which consubstantially high tensile strength in combination with a high degree of ductility. This combinatio'n has the advantages that over awide and tensile strength. fall comparativelyslowly,

thus giving a distinct advantage inheat treat-.

ment operation.

The invention provides an .alloy steel of the type containing small proportions of nickel and chromium (say up to 7% of each element) together with molybdenum, characterised in that the carbon content does not exceed 0.12%, while the molybdenum content is relatively high for this type of steel, namely of the order of 2 to 5%. More specifically, the invention consists'i n an alloy steel having the following composition? Perv cent Carbon 0 to0.12 Nickels 3 to 7 Chromium 3 to '7 Molybdenum s 2 to 5 v with or without the usual percentages of other ever, within the scope oi'the invention toadd somewhat higher proportions of manganese in produce the desired properties. If desired, tungsten may be added in quantities not exceeding 4 or 5%. l

erties obtained is as follows: v a

tains no great amountof carbon, and gives a range of tempering temperatures its hardness elements such as silicon and 'manganese, employed in steel making operations. It is, howquantities up to say 5%, as, this element tends to I 2 Claims. (01. -128 I This invention consists in a newfor improved Analysis Percent (Tests on 0.423" v diameter bar Treatment: Air cooled from 000 O. air cooled after tempering for 1 hour at-- 71.8 80. 4 53. 8 Maximum stress 85.5 87. 8 70. 6 Elongation .p'ercent.. 18. 4 20. 8 26.4 Reduction of area pcrccnt 53.0 56. 0 62.0 Izo test 38, 36, 34 37, 40, 37 57, 54, 56

Treatment: Oil quenched from 900 C.air cooled after tempering for 1 hour at Yield oint. atoms/sq. in 70.0 76.9 52. 2 Maxir um stress tons/sq.in 85.7 I 86.0 69.0 Elongation percent 8 (1) Reduction of area percen Izod test 37, 35, 37 39, 40, 42 56, 64, 62

theremainder iron, the alloy being quenched from about 900 C. and subsequently tempered and air cooled from the tempering temperature.

Carbon i; "Silicon i n 0.54

Manganese n-; o s 0.54 Nickel 5.00 Chromium 4.16 Molybdenum-" i c 3.18

g gg g fj fgg 050 700 750 s00 s50 000 950 1000 Aircoolcd 360 393 393 '39s 351 co mentsv 300 .377 393" 308 377 304 'Waterquenchei 360 386 375 388 388 375 MECHANICAL PROPERTIES x 1 Treated as 2. A high tensile alloy steel containing nickel above 3% and up to 7%, chromium 3-'7%, molybdenum above 2%and upto 5%, carbon a trace up to a maximum of 0.12% and the remainder being substantially all iron except incidental impurities, the alloy being air cooledirom about 900 C. and subsequently tempered for 1 hour and air cooled from the tempering temperature,

and the alloy having the following mechanical properties for the tempering temperatures given:

WILLIAM HERBERT HATFIELD. 

